Answer to Question 1
Answer: Using the bcc feature basically allows you to share an email secretly with someone else. As you write emails, you can apply two tests to decide if you should use a bcc and if it is ethical. 1) Are you intending to deceive the to recipient about who is receiving the email? 2) Can the recipient be disadvantaged or hurt if the material in the email is shared with the bcc readers and the recipient doesn't know it? If you can answer yes to either of these two questions, then do not use the bcc feature.
Answer to Question 2
Answer: While showing appreciation for the effort someone has made is always a good idea, it is important to communicate thanks in a way that is culturally appropriate. Different cultures have different ways of expressing thanks and perhaps different expectations about length and the amount of detail. In the United States, a low-context culture, a message that is short and to the point is appropriate. In a high-context Asian culture, a thank-you message should be longer and more formal. At the beginning it should focus on the relationship between the writer and audience. In American culture there is low power distance, so a message between an employee and superior would be more informal than that in an Asian culture with high power distance.
Geometry of carbon bonding
Carbon Dioxide Phase Diagram
A Test for the Blind Spot
Hootie and the Blowfish - I Go Blind
Functional Groups of Carbon
Ho to calculate the ATP of a 12-Carbon fatty acid, beta oxidation